Genetic analysis reveals the putative native range and widespread double-clonal reproduction in the invasive longhorn crazy ant.

Clonal reproduction can provide an advantage for invasive species to establish as it can circumvent inbreeding depression which often plagues introduced populations. The world's most widespread invasive ant, Paratrechina longicornis, was previously found to display a double-clonal reproduction system, whereby both males and queens are produced clonally, resulting in separate male and queen lineages, while workers are produced sexually. Under this unusual reproduction mode, inbreeding is avoided in workers as they carry hybrid interlineage genomes. Despite the ubiquitous distribution of P. longicornis, the significance of this reproductive system for the ant's remarkable success remains unclear, as its prevalence is still unknown. Further investigation into the controversial native origin of P. longicornis is also required to reconstruct the evolutionary histories of double-clonal lineages. Here, we examine genetic variation and characterize the reproduction mode of P. longicornis populations sampled worldwide using microsatellites and mitochondrial DNA sequences to infer the ant's putative native range and the distribution of the double-clonal reproductive system. Analyses of global genetic variations indicate that the Indian subcontinent is a genetic diversity hotspot of this species, suggesting that P. longicornis probably originates from this geographical area. Our analyses revealed that both the inferred native and introduced populations exhibit double-clonal reproduction, with queens and males around the globe belonging to two separate, nonrecombining clonal lineages. By contrast, workers are highly heterozygous because they are first-generation interlineage hybrids. Overall, these data indicate a worldwide prevalence of double clonality in P. longicornis and support the prediction that the unusual genetic system may have pre-adapted this ant for global colonization by maintaining heterozygosity in the worker force and alleviating genetic bottlenecks.

Decomposition of methanol-d4 on Au-Rh bimetallic nanoclusters on a thin film of Al2O3/NiAl(100).

The decomposition of methanol-d4 that was adsorbed on Au-Rh bimetallic nanoclusters grown by the sequential deposition of Au and Rh vapors onto ordered thin-film Al2O3/NiAl(100) at 300 K, occurred by means of dehydrogenation and primarily on the surface Rh. Nevertheless, the surface Rh atoms were not equally reactive; their reactivity altered with both structural and electronic effects arising from the alloying. The Au deposited on Rh clusters decorated the surface and deactivated Rh by not only directly obstructing them but also by neighboring them. As the initially incorporated Au tended to aggregate around reactive low-coordinated Rh atoms, such as corner Rh atoms, the reactivity of the cluster, indicated by the CO and deuterium (D2) produced per surface Rh, decreased markedly. In contrast, the Rh deposited on Au clusters promoted their reactivity. The reactivity was sharply enhanced by a few incorporated Rh atoms, as they preferentially decorated the edge Au atoms, resulting in their lower coordination, more positive charge, higher energetic d-band centers, and high reactivity. On the reactive Rh, the scission of the O-D bond in the initial dehydrogenation of methanol-d4 became more preferential than the competing desorption. The further incorporated Rh failed to promote the reactivity, but the clusters remained more reactive than those formed by Rh clusters incorporating Au as their structuring involved an active atomic segregation that yielded more low-coordinated and reactive surface Rh.

Formation and structures of Au-Rh bimetallic nanoclusters supported on a thin film of Al2O3/NiAl(100).

Self-organized alloying of Au with Rh in nanoclusters on an ordered thin film of Al2O3/NiAl(100) was investigated via various surface probe techniques under ultrahigh-vacuum conditions and calculations based on density-functional theory. The bimetallic clusters were formed on the sequential deposition of vapors of Au and Rh onto Al2O3/NiAl(100) at 300 K. The formation was more effective on the oxide seeded with Rh, since all post-deposited Au joined the pregrown Rh clusters; for metal deposition in the reverse order, some separate Rh clusters were formed. The contrasting behavior is rationalized through the easier nucleation of Rh on the oxide surface, due to the stronger Rh-oxide and Rh-Rh bonds. The alloying in the clusters proceeded, regardless of the order of metal deposition, toward a specific structure: an fcc phase, (100) orientation and Rh core-Au shell structure. The orientation, structural ordering and lattice parameters of the Au-Rh bimetallic clusters resembled Rh clusters, rather than Au clusters, on Al2O3/NiAl(100), even with Rh in a minor proportion. The Rh-predominated core-shell structuring corresponds to the binding energies in the order Rh-Rh > Rh-Au > Au-Au. The core-shell segregation, although active, was somewhat kinetically hindered, since elevating the sample temperature induced further encapsulation of Rh. The bimetallic clusters became thermally unstable above 500 K, for which both Rh and Au atoms began to diffuse into the substrate. Moreover, the electronic structures of surface elements on the bimetallic clusters, controlled by both structural and electronic effects, show a promising reactivity.

Surface structures and compositions of Au-Rh bimetallic nanoclusters supported on thin-film Al2O3/NiAl(100) probed with CO.

The surface structures and compositions of Au-Rh bimetallic nanoclusters on an ordered thin film of Al2O3/NiAl(100) were investigated, primarily with infrared reflection absorption spectra and temperature-programmed desorption of CO as a probe molecule under ultrahigh-vacuum conditions and calculations based on density-functional theory. The bimetallic clusters were formed by sequential deposition of vapors of Au and Rh onto Al2O3/NiAl(100) at 300 K. Alloying in the clusters was active and proceeded toward a specific structure-a fcc phase, (100) orientation, and Rh core-Au shell structure, regardless of the order of metal deposition. For Au clusters incorporating deposited Rh, the Au atoms remained at the cluster surface through position exchange and became less coordinated; for deposition in reverse order, deposited Au simply decorated the surfaces of Rh clusters. Both adsorption energy and infrared absorption intensity were enhanced for CO on Au sites of the bimetallic clusters; both of them are associated with the bonding to Rh and also a decreased coordination number of CO-binding Au. These enhancements can thus serve as a fingerprint for alloying and atomic inter-diffusion in similar bimetallic systems.

Molecular identification of the broodsacs from Leucochloridium passeri (Digenea: Leucochloridiidae) with a review of Leucochloridium species records in Taiwan.

Leucochloridium spp. have been established in Taiwan since the 1930s, with five species listed: Leucochloridium turdi, Leucochloridium passeri, Leucochloridium muscularae, Leucochloridium sime, and Leucochloridium taiwanese listed until now. Because of the similar morphology among the adults of the Leucochloridiidae family, the taxonomic status of most of them should be reconsidered. Broodsacs are the most distinct characteristic shared by Leucochloridium flukes, and L. passeri is, by far, the only one whose broodsacs have been described. In this study, broodsacs collected from an infected Succinea sp. (amber snails) in Taiwan were morphologically compared to previous descriptions and sequenced using both nuclear and mitochondrial genetic markers for identification. Our samples resembled broodsacs of L. passeri previously described in northern Taiwan and those recently collected in Okinawa, Japan. The conspecific status of the broodsacs collected in Taiwan and Okinawa was supported by the identical DNA sequences identified in this study. Broodsacs have rarely been reported in tropical and subtropical regions, although some Leucochloridium spp. have been recorded. In such cases, genetic markers will be crucial to link Leucochloridium broodsacs in snails (intermediate host) with their corresponding adult stage in birds (definitive host).

Laboratory and Field Evaluations of Two Bait Formulations Against the Invasive Fire Ant, Solenopsis invicta (Hymenoptera: Formicidae).

The red imported fire ant, Solenopsis invicta Buren, was first discovered in Japan in 2017. As this ant remains at the early invasion stage, efforts in establishing a rapid-response framework, such as evaluating available control methods, are urgently needed. Despite the presence of numerous household insecticides against invasive/household pest ants in Japan, the effects of these products on fire ants remain poorly understood. This study assessed the efficacy of two bait products designed to target common household ant pests in Japan on S. invicta through under laboratory and field conditions in Taiwan. The two baits are Arino-su-korori (AK), a granule-formulated bait product with hydramethylnon as an active ingredient (A.I.), and Hyper Arino-su-korori (HAK), a paste-formulated bait with fipronil as A.I., respectively. We showed that both AK and HAK resulted in more than 99% mortalities of fire ant within 8 wk under laboratory conditions and significantly reduce fire ants' foraging activities in the field. AK generally performed slightly better than HAK in terms of the time required to achieve total laboratory colony elimination and also long-term suppression of field fire ants. Such differences most likely are attributable to the active ingredient's mode of action and/or formulation and their interactions with fire ant biology. This study demonstrates the feasibility of the two bait products in effectively controlling laboratory and field fire ants, thus representing a promising candidate pest management tool to cope with ongoing/future fire ant invasions in Japan.

Dependence on Size of Supported Rh Nanoclusters in the Dehydrogenation of Methanol-d4 Obstructed by CO.

The size effect on the activity of a catalyst has been a focal issue since ideal catalysts were pursued, whereas that on the degradation of a catalyst, by reaction intermediates such as CO, is little discussed. We demonstrate that the dehydrogenation of methanol-d4 on supported Rh nanoclusters precovered with CO (Rh-CO clusters) was obstructed, indicated by a decreased production of CO and D2; the obstructive effect exhibits a remarkable dependence on the cluster size, with a minimum at a cluster diameter near 1.4 nm. The decreased production arose from a decreased reaction probability controlled by the increased activation energy for each dehydrogenation step (including formation of methoxy-d3), adsorption energies of CO, and repulsion from the CO array on the Rh-CO surface. The effects of these factors in deactivating the clusters varied separately with the cluster size. Consequently, the size effect on the CO poisoning should be taken into account in engineering the cluster size to optimize the catalytic performance.

Promoted activity of annealed Rh nanoclusters on thin films of Al2O3/NiAl(100) in the dehydrogenation of Methanol-d4.

Annealed Rh nanoclusters on an ordered thin film of Al2O3/NiAl(100) were shown to exhibit a promoted reactivity toward the decomposition of methanol-d4, under both ultrahigh vacuum and near-ambient-pressure conditions. The Rh clusters were grown with vapor deposition onto the Al2O3/NiAl(100) surface at 300 K and annealed to 700 K. The decomposition of methanol-d4 proceeded only through dehydrogenation, with CO and deuterium as products, on Rh clusters both as prepared and annealed. Nevertheless, the catalytic reactivity of the annealed clusters, measured with the production of either CO or deuterium per surface Rh site from the reaction, became at least 2-3 times that of the as-prepared ones. The promoted reactivity results from an altered support effect associated with an annealing-induced mass transport at the surface. Our results demonstrate a possibility to practically prepare reactive Rh clusters, regardless of the cluster size, that can tolerate an elevated reaction temperature, with no decreased reactivity.

Evidence for Common Horizontal Transmission of Wolbachia among Ants and Ant Crickets: Kleptoparasitism Added to the List.

While Wolbachia, an intracellular bacterial symbiont, is primarily transmitted maternally in arthropods, horizontal transmission between species has been commonly documented. We examined kleptoparasitism as a potential mechanism for Wolbachia horizontal transmission, using ant crickets and their host ants as the model system. We compared prevalence and diversity of Wolbachia across multiple ant cricket species with different degrees of host specificity/integration level. Our analyses revealed at least three cases of inter-ordinal Wolbachia transfer among ant and ant crickets, and also showed that ant cricket species with high host-integration and host-specificity tend to harbor a higher Wolbachia prevalence and diversity than other types of ant crickets. This study provides empirical evidence that distribution of Wolbachia across ant crickets is largely attributable to horizontal transmission, but also elucidates the role of intimate ecological association in successful Wolbachia horizontal transmission.

Real-time freehand 3D ultrasound calibration.

Z-fiducial phantoms allow three-dimensional ultrasound probe calibration with a single B-scan. One of the main difficulties in using this phantom is the need for reliable segmentation of the wires in the ultrasound images, which necessitates manual intervention. In this article, we have shown how we can solve this problem by mounting a thin rubber membrane on top of the phantom. The membrane is segmented automatically and the wires can be easily located as they are at known positions relative to the membrane. This enables us to segment the wires automatically at the full PAL frame rate of 25 Hz, to produce calibrations in real-time, while achieving accuracies similar to those reported in the literature. We have also devised a technique to improve the estimation of the elevational offset (calibration parameter) by capturing a few images of the planar membrane. If spatial calibration is known, fully automatic wire segmentation allows the fiducials to be tracked in real-time. This also enables temporal calibration to be performed in real-time as the probe is moved away from the phantom. We have evaluated the performance of our phantom by calibrating a probe at 8 cm and 15 cm depth. The precision of the calibrations are 0.7 mm and 1.2 mm, respectively. The point reconstruction accuracies of fiducial points provided by the same Z-phantom are slightly below 1.5 mm. The point reconstruction accuracies obtained by scanning the end of a wire tip are 2.5 mm and 3.0 mm. These results match the accuracies achieved in the literature. It takes approximately 2 min to set up the experiment, submerge the phantom in the water bath, locate the phantom in space with a pointer and capture six images of the planar membrane. After this, spatial calibration can be performed in less than a second. Temporal calibration can be completed in approximately 3 s.

Taxonomic notes on the genus Protanilla (Hymenoptera: Formicidae: Leptanillinae) from Taiwan.

A new species of Protanilla Taylor, 1990, P. jongi sp. nov., from Taiwan is described and illustrated, along with a supplementary description of the queen morphology of P. lini Terayama, 2009 and biological notes of Protanilla species. Furthermore, Furcotanilla Xu, 2012 is considered a junior synonym of Protanilla on reanalysis of purported diagnostic characters. A key to the world fauna of genus Protanilla based on the worker caste is provided.

Rapid, easy and reliable calibration for freehand 3D ultrasound.

This paper presents improvements to the plane-based technique for calibrating freehand 3D ultrasound systems. The improvements are designed to make it easier for inexperienced users to perform plane-based calibration and to know that they have got a reliable result. In particular, we enable the calibration to be performed using water at room temperature while producing a result that is valid for average soft tissue and we show how it is possible to provide feedback on the reliability of the calibration using a metric based on the curvature of the calibration criterion function. We present comprehensive results showing that these innovations improve the precision of the calibration and offer useful feedback to the user.

Comparison of freehand 3-D ultrasound calibration techniques using a stylus.

In a freehand 3-D ultrasound system, a probe calibration is required to find the rigid body transformation from the corner of the B-scan to the electrical center of the position sensor. The most intuitive way to perform such a calibration is by locating fiducial points in the scan plane directly with a stylus. The main problem of this approach is the difficulty in aligning the tip of the stylus with the scan plane. The thick beamwidth makes the tip of the stylus visible in the B-scan, even if the tip is not exactly at the elevational center of the scan plane. We present a novel stylus and phantom that simplify the alignment process for more accurate probe calibration. We also compare our calibration techniques with a range of styli. We show that our stylus and cone phantom are both simple in design and can achieve a point reconstruction accuracy of 2.2 mm and 1.8 mm, respectively, an improvement from 3.2 mm and 3.6 mm with the sharp and spherical stylus. The performance of our cone stylus and phantom lie between the state-of-the-art Z-phantom and Cambridge phantom, where accuracies of 2.5 mm and 1.7 mm are achieved.